I'm thinking of buying small income generating properties for retirement income.

BUT there is a vacant commercial lot for sale, in a newly opened wide road that has several developers (DMCI and SMDC) that are putting up condos and townhouses along the same road. All the commercial lots are gigantic, but there is one small lot left! And so...I'm tempted to get it, hold it and sell in a few years, or even build a small commercial building.

What would you guys do? Buy sure income properties(all tenanted, income of 7-10% of value of property), or speculate on a lot that has a future upside?

Either way will yield positive result, but I wouldn't compare that to bonds because as you mentioned earlier you can get a coupon rate of 7-10% per annum and its a commercial lot so it is sustainable. In bonds you cannot get that rate in a long period of time.

For me its buy, build and hold property I wouldn't sell that unless you see TEL at 1200 pesos or MWC at 14 pesos!hehehe

Real estate investing has its own set of risks though, and involves many more people, like a lawyer, broker, maintenance, etc., while buying stocks and bonds is as easy as a click of the mouse of your computer.